The reason why there is no mention of flying hours because it has very little to do with flying pay (other than the title).
The idea behind flying pay is a recruitment and retention initiative. If you PVR you aren't being retained, therefore your flying pay is cut.
Gunners who are getting the retention bonus aren't given a quota for deployments (AFAIUI) but they are leeching like nobodies business and the only way (it seems) to keep them in is to give them more money. If the MOD decided to do away with flying pay, then the aircrew would walk to civvie street, either to fly in the airlines or some other sector or for those who can't pilot, work somewhere else.
The MOD is slowly realising that it needs to pay its staff more to keep them in if they can't sort out all the other push factors, but funny old thing they can't afford to pay the sort of money to keep them in!!
